Journal of Clinical Oncology, 2005 ASCO Annual Meeting Proceedings.
Vol 23, No 16S (June 1 Supplement), 2005: 529
© 2005 American Society of Clinical Oncology

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Abstract

Optimizing endocrine therapy in postmenopausal women with early stage breast cancer: A decision analysis for biological subsets of tumors

Dana-Farber Cancer Inst, Boston, MA; Harvard Medcl Sch, Boston, MA

529

Background: Choices for adjuvant endocrine therapy in postmenopausal breast cancer patients include sequential treatment with tamoxifen and then aromatase inhibitors, or upfront therapy with an aromatase inhibitor. Available data do not define which strategy would be optimal. Previously we modeled these strategies and found that sequential therapy with tamoxifen followed by crossover to an aromatase inhibitor at 2.5 years yielded superior 10-year disease-free survival (DFS) than treatment with either tamoxifen or aromatase inhibitor treatment, alone (SABCS 2004). Based on emerging data, we sought to analyze whether the optimal treatment strategy would differ for ER+PgR+ and ER+PgR- tumors. Methods: We developed a Markov model to simulate 10-year DFS among a cohort of postmenopausal women with hormone-receptor positive breast cancer. Treatment strategies analyzed were aromatase inhibitor alone, tamoxifen alone, or tamoxifen followed by crossover to an aromatase inhibitor at 2 years. Risk estimates were derived from reports of randomized clinical trials. Results: The optimal treatment strategy differed based on the biological features of the tumor. The 10-year DFS estimates are shown in the Table. Two-way sensitivity analyses suggest these findings are robust across the range of hazard ratios reported inthe ATAC, ARNO/ABCSG, and IES trials, and provide a framework for evaluating future data from related trials. Conclusions: Modeling estimates suggest that the optimal adjuvant endocrine strategy in postmenopausal patients may differ based on the biological features of the tumor. Sequential tamoxifen then aromatase inhibitor treatment after 2 years appears superior for ER+PgR+ tumors, but upfront treatment with an aromatase inhibitor may yield superior outcomes for ER+PgR- tumors. Clinicians and patients may find this information useful while awaiting results from prospective randomized trials.

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Abstract presentation from the 2005 ASCO Annual Meeting